This application is a RCE application of 09/222,476, filed Dec. 29, 1988.
Magnetostrictive effect is a term describing a change in the size of a magnetic substance upon exposure to an external magnetic field. Joule effect is a term describing a change in the length of a ferromagnetic substance, in a direction parallel to an externally applied magnetic field. All electromagnetic devices, apparatuses and machines are subject to the magnetostrictive effect and the Joule effect.
For a specific example, the magnetic field in an electromagnetic device, apparatus and machine causes a net change in the size of a core thus generating vibratory energy, which vibratory energy may consequently cause unwanted noise and premature component fatigue leading to part failures.
There are several patents addressing the issues of the magnetostrictive effect and the Joule effect, which patents are discussed in some detail hereinbelow.
Hibino et al. discloses a Magnetic Core for AC Electrical Equipments (U.S. Pat. No. 5,172,020). This reference purportedly attempts to deal with harmonic fluxes, distorting electric fields, frequency fluxes and electromagnetic noises. It teaches using a high silicon steel and a low silicon steel as lamination materials. Both materials are known to expand under the influence of electromagnetic field, but one expands at a greater rate than the other.
Yun discloses an Electric Generator Utilizing Minimal Mechanical Power (U.S. Pat. No. 5,420,471). This patent mainly teaches alternately laminating ferromagnetic and non-ferromagnetic materials together to form a stator core of a generator, for the purpose of achieving a weak magnetic field so that it would be easy to turn a rotor of the generator. Yun has not disclosed eliminating vibrations caused by magnetostrictive effect or preventing any magnetic field leakage.
Moore discloses a Motor Control (U.S. Pat. No. 2,456,982). This patent mainly discloses using a motor controller to control a furnace. It has not disclosed or taught any concerns over magnetostrictive expansion, physical vibration, or magnetic leakage. The only pertinent aspect of Moore is the disclosure of alternately laminating different materials, each with different widths to poles N1 and S1, as shown in FIG. 3. However in Moore, this is done for the purpose of increasing reluctance, thus, torque of the motor.
Edson discloses an Operation of Magnetostrictive Apparatus (U.S. Pat. No. 3,753,058) and a Magnetostrictive Apparatus and Process (U.S. Pat. No. 3,634,742). Both patents teach using magnetostrictive material to increase the amount of material expansion and contraction for the purpose of inducing physical vibration. There is no disclosure or teaching of eliminating physical vibrations.
The present invention teaches laminating a magnetostrictive contracting material with a magnetostrictive expanding material so that the virtually equal amount of contraction and expansion will prevent or minimize the generation of vibratory energy and noise when the cores made of these materials are subjected to a magnetic field.